import { execFile } from "node:child_process";
import { existsSync } from "node:fs";
import { join } from "node:path";
import { pathToFileURL } from "node:url";
import type { HooksData } from "../../web/lib/remaining-command-types.ts";
import { resolveBridgeRuntimeConfig } from "./bridge-service.ts";
import {
	buildSubprocessPrefixArgs,
	resolveSubprocessModule,
} from "./ts-subprocess-flags.ts";

const HOOKS_MAX_BUFFER = 512 * 1024;
const HOOKS_MODULE_ENV = "SF_HOOKS_MODULE";

function resolveTsLoaderPath(packageRoot: string): string {
	return join(
		packageRoot,
		"src",
		"resources",
		"extensions",
		"sf",
		"tests",
		"resolve-ts.mjs",
	);
}

/**
 * Collects hook configuration and status via a child process.
 * Runtime state (active cycles, hook queue) is not available in a cold child
 * process, so activeCycles will be empty. The child calls getHookStatus() which
 * reads from preferences to build entries, then formatHookStatus() for display.
 */
export async function collectHooksData(
	projectCwdOverride?: string,
): Promise<HooksData> {
	const config = resolveBridgeRuntimeConfig(undefined, projectCwdOverride);
	const { packageRoot, projectCwd } = config;

	const resolveTsLoader = resolveTsLoaderPath(packageRoot);
	const moduleResolution = resolveSubprocessModule(
		packageRoot,
		"resources/extensions/sf/post-unit-hooks.ts",
	);
	const hooksModulePath = moduleResolution.modulePath;

	if (
		!moduleResolution.useCompiledJs &&
		(!existsSync(resolveTsLoader) || !existsSync(hooksModulePath))
	) {
		throw new Error(
			`hooks data provider not found; checked=${resolveTsLoader},${hooksModulePath}`,
		);
	}
	if (moduleResolution.useCompiledJs && !existsSync(hooksModulePath)) {
		throw new Error(
			`hooks data provider not found; checked=${hooksModulePath}`,
		);
	}

	// getHookStatus() internally calls resolvePostUnitHooks() and resolvePreDispatchHooks()
	// from preferences.ts, which read from process.cwd()/.sf/PREFERENCES.md.
	// We set cwd to projectCwd so preferences resolution finds the right files.
	// In a cold child process, cycleCounts is empty, so activeCycles will be {}.
	const script = [
		'const { pathToFileURL } = await import("node:url");',
		`const mod = await import(pathToFileURL(process.env.${HOOKS_MODULE_ENV}).href);`,
		"const entries = mod.getHookStatus();",
		"const formattedStatus = mod.formatHookStatus();",
		"process.stdout.write(JSON.stringify({ entries, formattedStatus }));",
	].join(" ");

	const prefixArgs = buildSubprocessPrefixArgs(
		packageRoot,
		moduleResolution,
		pathToFileURL(resolveTsLoader).href,
	);

	return await new Promise<HooksData>((resolveResult, reject) => {
		execFile(
			process.execPath,
			[...prefixArgs, "--eval", script],
			{
				cwd: projectCwd,
				env: {
					...process.env,
					[HOOKS_MODULE_ENV]: hooksModulePath,
				},
				maxBuffer: HOOKS_MAX_BUFFER,
				windowsHide: true,
			},
			(error, stdout, stderr) => {
				if (error) {
					reject(
						new Error(
							`hooks data subprocess failed: ${stderr || error.message}`,
						),
					);
					return;
				}

				try {
					resolveResult(JSON.parse(stdout) as HooksData);
				} catch (parseError) {
					reject(
						new Error(
							`hooks data subprocess returned invalid JSON: ${parseError instanceof Error ? parseError.message : String(parseError)}`,
						),
					);
				}
			},
		);
	});
}
